Diagnostico da exigencia do cafeeiro em nitrogenio pela utilizaçao do medidor portatil de clorofila

Abstract

Nitrogen is the most required nutrient by coffee crop and its management is very important. The losses of the nutrient are very important specially during rainy season. The study was developed in Sud Mennucci county (northwest of São Paulo State - Brazil) in an Alfisol in order to evaluate the effect of different rates and application times of nitrogen on the chlorophyll and nitrogen content in coffee leaves, and to establish correlations with the productivity. The experimental design was a complete randomized, in a factorial outline 5 × 3, constituted by combination of 5 rates (0, 50, 150, 250 and 350 kg ha-1) of nitrogen (urea) in three application times (a single application in December; two applications: splitted in November and January and three applications: splitted in November, December and January). The leaf chlorophyll content and nitrogen leaf content were evaluated during frutification and harvest. The chlorophyll concentration was positively correlated with the leaf nitrogen content and production of grains adjusted to a quadratic function to rates of applied N, in which the rate of 210 kg ha-1 of nitrogen promoted the greater productivity. The estimative of the chlorophyll content seemed to be a prospective means for detection of N deficiencies in coffee crop.